This invention relates to data entry devices and, in particular, to data entry devices for entering keyed data and graphical information.
Keyboards which employ actuatable keys are well known devices for use in entering information into a variety of information systems. Thus, for example, in computer systems a keyboard whose keys correspond to alphanumeric characters is used for entry of data to the system. When a key of the keyboard is actuated, the integrated circuitry of the keyboard generates an information signal which is fed to the CPU of the computer system. The CPU recognizes this signal as the alphanumeric character associated with the key and the CPU then addresses a display, typically a cathode ray tube (CRT), instructing the display to depict the character so that the user can verify that the correct information has been entered.
In many computer systems, it has been found desirable to have the capability of also directly entering into the system handwritten and graphical information. This has been accomplished by providing, in addition to the keyboard, a separate input unit which is likewise connected to the computer. This unit includes an extended, two dimensional first member (sometimes referred to as a "tablet") and a second member (sometimes referred to as a "stylus" or "cursor") capable of designating a position on the first member. The nature of these members is such that when the second member is brought in proximity to a position to be designated on the first member, a signal or signals are developed which are indicative of the designated position. These signals are then detected and fed to the computer CPU which recognizes the signals as identifiying the designated position. The CPU then stores this information and also feeds it to the CRT display which depicts the position. By moving the second member, successive positions corresponding to a graphical representation can be designated, stored by the CPU and displayed by the CRT.
There are presently available numerous types of units employing first and second member combinations of this type, or their equivalents. One type of unit makes use of an electromagnetic coupling between a coil in the second member and a grid of planar wires situated in the first member. In this type of arrangement, the signals to and from the grid are fed through a conversion board or circuit which converts the signals to positional signals identifiable by the computer CPU. These types of arrangements are disclosed, for example in U.S. Pat. Nos. 4,570,033 and 4,552,991. Units of this type are also sold as so-called "digitizers" by Numonics Corp under Model No. 2210.
Another type of arrangement makes use of a first member comprised of a resistive layer which is contacted by the second member to generate the positional signals. An arrangement of this type is disclosed, for example, in U.S. Pat. No. 4,653,086. Other types of coupling used between the first and second members might be acoustic, optical, resistive, capacitive, electromagnetic, ultrasonic and piezoelectric.
In the systems in use today, since the above graphical units are separate attachments to the computer system along with the aforementioned keyboards, they increase the overall space requirements for the computer equipment which is undesirable from the users standpoint.
It is therefore, a primary object of the present invention to provide an apparatus having the capability of entering keyed information as well as graphical information.